Between Mars and Jupiter stretches a wide zone filled with rocky asteroids. These are not pieces of a planet that exploded. They are leftover building blocks from when the solar system formed. Small chunks never grew big enough to become a full planet. Instead they drift in a loose ring, orbiting the Sun together. From far away the belt looks crowded in movies, but space is huge and asteroids are usually very far apart.
🎬 MYTH
In real life, spacecraft can fly through the belt without hitting rocks constantly. Asteroids are spread across a vast volume of space.